Question

我尝试使用经过身份验证的SSL连接和下面的类中定义的一些控制消息在客户端和服务器之间编写一个简单的协议：

public class KeyExchangeProtcolMsgs {
    public static final String reqStr = "#REQ_KM";
    public static final String nonceStr = "#NONCE_END";
    public static final String ackStr = "#ACK_KM";
}

client.java

        // Connect to the server
        cSock = (SSLSocket) fact.createSocket(this.remoteHost, this.remotePort);
        // Create the streams to send out data as well as read data
        OutputStream out = cSock.getOutputStream();
        InputStream in = cSock.getInputStream();
        // Generate client nonce
        byte[] clientNonceB = CryptographyUtils.generateRandomNumber();
        // Send the nonce and the request for a key from the server
        // First, send the keying material request to the server
        System.out.println("[I] SSL client written " + KeyExchangeProtcolMsgs.reqStr);
        out.write(CryptographyUtils.toByteArray(KeyExchangeProtcolMsgs.reqStr)); // <== Successfully written to the server
        // Next, send the generated nonce (by the client)
        System.out.println("[I] SSL client written nonce ");
        System.out.println(new String(clientNonceB, "UTF-8"));
        out.write(clientNonceB);
        // Finally, send the ending string
        System.out.println("[I] SSL client written " + KeyExchangeProtcolMsgs.nonceStr);
        out.write(CryptographyUtils.toByteArray(KeyExchangeProtcolMsgs.nonceStr));
        // Wait for the response from the server containing the key
        int ch = 0;
        String responseStr = "";
        while ((responseStr.contains(KeyExchangeProtcolMsgs.ackStr) == false) && (responseStr.contains(KeyExchangeProtcolMsgs.nonceStr) == false)) {
            ch = in.read();
            responseStr = responseStr + (char) ch;
            System.out.println("[I] SSL client read " + responseStr);
        }
        // Display read information from server
        System.out.println("[I] SSL client read " + responseStr);
        // Check if the server nonce contains the starting and end messages of the protocol

            String serverNonceStr = responseStr.substring(KeyExchangeProtcolMsgs.ackStr.length(), responseStr.length() - KeyExchangeProtcolMsgs.nonceStr.length());
            // Compute the key by xor-ing the client and server nonce and applying AES
            // on the resulting string
            clientKeyingMaterial = new SecretKeySpec(CryptographyUtils.xorStrings(clientNonceB, CryptographyUtils.toByteArray(serverNonceStr)), "AES");
            return clientKeyingMaterial;

server.java

        System.out.println("[I] SSL server listening");

        SSLSocket sslSock = (SSLSocket) sSock.accept();
        sslSock.startHandshake();

        System.out.println("[I] SSL server starting handshake");

        // Process if principal checks out
        if (isEndEntity(sslSock.getSession())) {
            // Create the streams to send out data as well as read data
            OutputStream out = sslSock.getOutputStream();
            InputStream in = sslSock.getInputStream();
            // Wait and read the client's nonce
            int ch = 0;
            String requestStr = "";
            while ((requestStr.contains(KeyExchangeProtcolMsgs.reqStr) == false) && (requestStr.contains(KeyExchangeProtcolMsgs.nonceStr) == false)) {
                ch = in.read();
                requestStr = requestStr + (char) ch;
                System.out.println("[I] SSL server received " + requestStr);
            }

            System.out.println("[I] SSL server received " + requestStr);
         }

一旦 KeyExchangeProtcolMsgs.reqStr /＃REQ_KM 被发送，服务器端的循环就会退出但不等待实际的现时和结束消息 KeyExchangeProtcolMsgs.nonceStr /＃NONCE_END

为什么服务器端while循环在客户端发送最后一条消息之前退出？

Answer 1

因为只要requestStr包含KeyExchangeProtcolMsgs.reqStr，requestStr.contains(KeyExchangeProtcolMsgs.reqStr)就会变成true，所以requestStr.contains(KeyExchangeProtcolMsgs.reqStr) == false变为true == false，即false因此，while循环中的整个测试变为false，因此执行将从while循环中退出。

有几种方法可以解决这个问题，最简单的方法是使用两个while循环。第一个只是循环，直到requestStr为KeyExchangeProtcolMsgs.reqStr，第二个累积nonce直到它以KeyExchangeProtcolMsgs.nonceStr结束。像这样：

        String requestStr = "";
        while (!requestStr.equals(KeyExchangeProtcolMsgs.reqStr)) {
            ch = in.read();
            requestStr = requestStr + (char) ch;
        }

        System.out.println("[I] SSL server received " + requestStr);

        String nonceStr = "";
        while (!requestStr.endsWith(KeyExchangeProtcolMsgs.nonceStr)) {
            ch = in.read();
            nonceStr = nonceStr + (char) ch;
        }

        // Whack #NONCE_END from the end to get just the nonce.

        nonceStr = nonceStr.substring(0, nonceStr.length() - KeyExchangeProtcolMsgs.nonceStr.length());

        System.out.println("[I] SSL server received " + nonceStr);

未经测试但应该接近。

您可以通过保留某种状态指示符来执行单个while循环，以便您知道何时累积reqStr以及何时累积nonceStr，但我认为像这样拆分更清洁。

从SSL输入流（Java）读取

1 个答案: